Preheat your oven to 375°F / 190°C.

Cook the lasagna noodles according to package directions until al dente.

Drain in a colander, rinse with cold water to stop the cooking process, and drain well again. Lay the noodles in a single layer on a sheet of foil to prevent them from sticking.

While the pasta cooks, prepare the vegetable fillings.

In a large skillet, heat 1 tablespoon (15 ml / 0.5 fl oz) of olive oil over medium-high heat.

Add the carrots, zucchini, and half of the minced garlic.

Sauté for about 5 minutes until the vegetables are crisp-tender.

Transfer this mixture to a large bowl.

In the same skillet, heat the remaining 1 tablespoon (15 ml / 0.5 fl oz) of oil.

Add the mushrooms and the rest of the garlic, and sauté for 5 minutes until tender.

Add the spinach to the skillet in batches, stirring continuously for 1-2 minutes until it is completely wilted. Use a slotted spoon to move the spinach and mushroom mixture to a separate bowl, leaving any excess liquid behind.

Stir the fresh basil into this mixture.

In a third bowl, prepare the cheese filling by stirring together the lightly beaten egg, ricotta cheese, Parmesan cheese, salt, and pepper until well combined.

It's time to assemble your lasagna pie!

In the bottom of a 9x3-inch springform pan, spread 1/2 cup (480 ml) of the pasta sauce. Create the first layer by arranging 3-4 cooked noodles over the sauce, trimming and overlapping them as needed to form a solid base.

For the next layers: Top the noodles with half of the spinach-mushroom mixture, followed by half of the ricotta mixture.

Add another layer of noodles.

Spread half of the remaining pasta sauce over the noodles, then top with all of the carrot-zucchini mixture and sprinkle with 1 cup (240 ml) of the fontina cheese.

Add a third layer of noodles.

Spread the remaining spinach-mushroom mixture and the remaining ricotta mixture on top.

Finish with a final layer of noodles and the rest of the pasta sauce. Gently press down on the top with a spatula to compact the layers.

Place the springform pan on a foil-lined baking sheet to catch any drips.

Bake, uncovered, for 45 minutes.

Sprinkle the remaining 1 cup (240 ml) of fontina cheese over the top and bake for another 15 minutes, or until the cheese is melted and bubbly and the pie is heated through.

Carefully remove the lasagna from the oven and let it stand on a wire rack for 15 minutes. This is crucial for it to set!

After resting, run a knife around the edge of the pan and carefully remove the sides.

Garnish with fresh rosemary sprigs if desired, then slice into wedges and serve.

Don't overcook your pasta.

Cook the noodles just until al dente, as they will continue to soften while baking in the oven. This prevents a mushy final texture.

Squeeze the spinach dry.

After wilting the spinach, let it cool for a moment and then squeeze out as much excess water as possible. This is the key to preventing a watery lasagna.

Let it rest. The 15-minute standing time after baking is non-negotiable! It allows the layers to set, ensuring you can cut clean, beautiful slices that hold their shape.